The present invention relates to a method or process of bridging between contour elements in an image. It applies more particularly to the recognition of vessels in digital angiography but may also apply to the analysis of aerial views for the recognition of rivers and roads.
Angiography is a process permitting visual analysis of blood vessels. It principally consists in X-raying the zone of observation before then after injection of a product opaque to the X-rays. The logarithmic difference of these two images, if there is no movement between the two images, allows a well contrasted image to be obtained of the zones of the vascular network where theproduct has diffused. The support for the image is formed, in digital angiography, by a digital image memory allowing the observed zones of the vascular network to be analysed practically in real time. Only the contour lines of the vascular network are restored discontinuously because of the thresholds used in the contour extraction methods. It is consequently necessary to determine whether these discontinuities are due to a real absence of contours or if, on the contrary, they are caused by a local minimum of the luminance gradient.
Known processes are generally based on considerations of proximity or orientation at the ends of the contour lines likely to be bridged, but these processes are still imprecise and give no information with sufficient certainty about the real presence or absence of discontinuities in the vascular network.